Arkansas scrimmaged for 138 plays Thursday evening in Donald W. Reynolds Razorback Stadium, but it was difficult for anyone to concentrate after the seventh play when Heisman Trophy candidate Knile Davis went down yelling in agony with a serious ankle injury. He is expected to miss the entire 2011 season.

The entire stadium went silent on the seventh play except for his voice echoing off the stands. Players watched as if to say 'oh no, not Knile.' Razorbacks head coach Bobby Petrino commented on the situation Friday morning.

"I am extremely disappointed for Knile," Petrino stated in a news release. "He is a captain who was incredibly focused on the upcoming year. His leadership throughout the offseason was significant in the development of this team. Our athletic trainers and medical staff are the best in the country, and Knile's mental toughness will be an asset to him during the recovery process. I am fully confident in the mindset of our running back group and their ability to perform."

Davis was a returning first-team All-SEC performer and a 2011 Heisman Trophy candidate after rushing 204 times for 1,322 yards (6.5 ypc) and 13 touchdowns last season. He broke his right ankle in high school and broke the same one again as a freshman due to the screws being too small after the first surgery. He has had no ill effects on the other ankle since his surgery.

Davis was having a fantastic camp after maxing out at 430 pounds in the bench press and running the 40-yard dash in 4.29 seconds at 6-0, 230 pounds in the spring. He had a great offseason and was impressive through all of the first eight fall camp workouts.

What now?

As great as Davis is, it is not as if Arkansas won't use a running back this year. Senior Broderick Green, the second-leading rusher last season, was lost for the year in the spring with a torn ACL. That leaves Ronnie Wingo and Dennis Johnson to carry the load.

Wingo has breakaway speed and is also dangerous as a receiver at 6-3, 233 pounds. He has been working to become more of an inside runner and to stop looking for the corner so much. In the spring, he was the most productive of all the tailbacks, including Davis, but neither he nor Johnson combine the total package of power, speed, elusiveness and experience that Davis provided. Last season, Wingo had 41 carries for 253 yards (6.2 ypc) with one touchdown. He also caught 27 passes for 274 yards (10.1 ypc) with 4 more scores. He has yet to carry the ball more than 9 times in a game for his career.

Johnson brings some game-breaking ability with his talent to break tackles and make long runs at 5-9, 213. He was lost for the season in 2010 with a bizarre bowel injury during the second game of the season against Louisiana-Monroe. He does however have some notable games, including 14 carries for 107 yards against Florida in 2009, and 18 carries for 127 yards and a touchdown against LSU in 2008.

The Razorbacks also have true freshman big back Kody Walker, 6-2, 245, and have used wide receiver Joe Adams in the backfield in the past with success. It is also possible that true freshman Kelvin Fisher Jr. is moved from cornerback to tailback to improve numbers. Senior cornerback De'Anthony Curtis played tailback his first two years on campus and could get a look, as well.

The concern for Arkansas is not putting points on the board. Junior quarterback Tyler Wilson has been impressive the past two practices, going 12 of 14 for 197 yards and 2 touchdowns in Wednesday's team work and 16 of 20 for 247 yards and 4 touchdowns in Thursday's scrimmage. He has a number of standout wide receivers at his disposal and someone most consider an offensive genius as a play-caller in Petrino.

The concern is the low number of tailbacks now on the roster and whether or not Arkansas will be able to put a game away in the fourth quarter, something the Hogs struggled with last season until Davis emerged as the go-to back in the seventh game last season against Ole Miss, his first 20-carry game as a Razorback (22 for 176 and three touchdowns). Before that, the Hogs almost lost at Georgia because they could not put it away on the ground, and it also cost them the Alabama game at home.